Wireless communication may take place within in a dedicated spectrum. For example, up to now, the spectrum used by Long-Term Evolution (LTE) cellular communications networks is dedicated to LTE. This has the advantage that an LTE system does not need to take into account any spectrum coexistence issues with other uses of the spectrum, and that spectrum efficiency can be maximized. However, the spectrum allocated to LTE is limited which may not be able to meet the ever increasing demand for larger throughput from applications and services.
Accordingly, consideration is being given to enabling wireless communication devices to be operable in unlicensed radio spectrums in addition to licensed spectrums. For example, “Licensed-Assisted Access” (LAA) may allow LTE equipment to also operate in the unlicensed 5 GHz radio spectrum. The unlicensed 5 GHz spectrum may be used as a complement to the licensed spectrum. Accordingly, devices may connect in the licensed spectrum (primary cell or PCell) and use carrier aggregation to benefit from additional transmission capacity in the unlicensed spectrum (secondary cell or SCell). Further, it is conceivable that standalone operation of LTE in an unlicensed spectrum may also be possible.
However, the present inventor has recognized that transmissions in an unlicensed spectrum present challenges. An unlicensed spectrum can, by definition, be simultaneously used by multiple different technologies. Therefore, communication by wireless devices in unlicensed spectrums needs to consider coexistence issues with other systems that may utilize the same spectrum, such as IEEE 802.11 (Wi-Fi). For example, operating LTE in the same manner in unlicensed spectrum as in licensed spectrum can seriously degrade the performance of Wi-Fi as Wi-Fi will not transmit once it detects that the channel is occupied.
Accordingly, it would be desirable to provide systems and methods that avoid the afore-described problems and drawbacks and which, more specifically, provide for methods and devices enabling wireless communication devices to operate in unlicensed radio spectrums in addition to licensed spectrums.